This invention relates to a method and apparatus for treating metal scrap cuttings and more particularly for preparing such cuttings for use in a powdery metal material, suitable for making sintered pieces.
The metal scrap cuttings used in this invention are scraps from machine tools which perform various well-known machining steps in the manufacture of parts for mechanical devices.
Heretofore these metal scraps have been a nuisance in that they present problems of storage, handling and rapid oxidation.
Despite their availability and generally small size, no proposal known to applicant has been made to use these scraps in preparation of metal powders intended for making sintered pieces in powder metallurgy processes. Conventionally, such metal powders are prepared by treatment of a molten metal material.
Raw metal scrap cuttings are not suitable for use in powder metallurgy processes because their abrasive physical state poses problems of handling, the cuttings having a tendency to wear the parts of the handling devices. Another problem arises from the cold working of these cuttings. When making sintered pieces from metallic powders, the presence of cold worked constituents in the powder can impede sintering.
Untreated machine tool cuttings, moreover, have a tendency particularly when heated, to form agglomerated masses unsuitable for making sintered pieces.